289 lines
7 KiB
C
289 lines
7 KiB
C
/*
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* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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*
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* SPDX-License-Identifier: MPL-2.0
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, you can obtain one at https://mozilla.org/MPL/2.0/.
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*
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* See the COPYRIGHT file distributed with this work for additional
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* information regarding copyright ownership.
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*/
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/*! \file */
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#include <stdbool.h>
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#include <isc/ascii.h>
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#include <isc/magic.h>
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#include <isc/mem.h>
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#include <isc/string.h>
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#include <isc/symtab.h>
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#include <isc/util.h>
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typedef struct elt {
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char *key;
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unsigned int type;
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isc_symvalue_t value;
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LINK(struct elt) link;
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} elt_t;
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typedef LIST(elt_t) eltlist_t;
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#define SYMTAB_MAGIC ISC_MAGIC('S', 'y', 'm', 'T')
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#define VALID_SYMTAB(st) ISC_MAGIC_VALID(st, SYMTAB_MAGIC)
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struct isc_symtab {
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/* Unlocked. */
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unsigned int magic;
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isc_mem_t *mctx;
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unsigned int size;
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unsigned int count;
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unsigned int maxload;
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eltlist_t *table;
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isc_symtabaction_t undefine_action;
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void *undefine_arg;
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bool case_sensitive;
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};
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isc_result_t
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isc_symtab_create(isc_mem_t *mctx, unsigned int size,
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isc_symtabaction_t undefine_action, void *undefine_arg,
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bool case_sensitive, isc_symtab_t **symtabp) {
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isc_symtab_t *symtab;
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unsigned int i;
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REQUIRE(mctx != NULL);
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REQUIRE(symtabp != NULL && *symtabp == NULL);
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REQUIRE(size > 0); /* Should be prime. */
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symtab = isc_mem_get(mctx, sizeof(*symtab));
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symtab->mctx = NULL;
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isc_mem_attach(mctx, &symtab->mctx);
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symtab->table = isc_mem_cget(mctx, size, sizeof(eltlist_t));
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for (i = 0; i < size; i++) {
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INIT_LIST(symtab->table[i]);
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}
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symtab->size = size;
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symtab->count = 0;
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symtab->maxload = size * 3 / 4;
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symtab->undefine_action = undefine_action;
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symtab->undefine_arg = undefine_arg;
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symtab->case_sensitive = case_sensitive;
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symtab->magic = SYMTAB_MAGIC;
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*symtabp = symtab;
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return ISC_R_SUCCESS;
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}
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void
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isc_symtab_destroy(isc_symtab_t **symtabp) {
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isc_symtab_t *symtab;
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unsigned int i;
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elt_t *elt, *nelt;
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REQUIRE(symtabp != NULL);
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symtab = *symtabp;
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*symtabp = NULL;
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REQUIRE(VALID_SYMTAB(symtab));
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for (i = 0; i < symtab->size; i++) {
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for (elt = HEAD(symtab->table[i]); elt != NULL; elt = nelt) {
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nelt = NEXT(elt, link);
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if (symtab->undefine_action != NULL) {
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(symtab->undefine_action)(elt->key, elt->type,
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elt->value,
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symtab->undefine_arg);
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}
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isc_mem_put(symtab->mctx, elt, sizeof(*elt));
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}
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}
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isc_mem_cput(symtab->mctx, symtab->table, symtab->size,
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sizeof(eltlist_t));
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symtab->magic = 0;
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isc_mem_putanddetach(&symtab->mctx, symtab, sizeof(*symtab));
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}
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static unsigned int
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hash(const char *key, bool case_sensitive) {
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const char *s;
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unsigned int h = 0;
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/*
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* This hash function is similar to the one Ousterhout
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* uses in Tcl.
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*/
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if (case_sensitive) {
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for (s = key; *s != '\0'; s++) {
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h += (h << 3) + *s;
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}
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} else {
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for (s = key; *s != '\0'; s++) {
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h += (h << 3) + isc_ascii_tolower(*s);
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}
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}
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return h;
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}
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#define FIND(s, k, t, b, e) \
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b = hash((k), (s)->case_sensitive) % (s)->size; \
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if ((s)->case_sensitive) { \
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for (e = HEAD((s)->table[b]); e != NULL; e = NEXT(e, link)) { \
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if (((t) == 0 || e->type == (t)) && \
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strcmp(e->key, (k)) == 0) \
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break; \
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} \
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} else { \
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for (e = HEAD((s)->table[b]); e != NULL; e = NEXT(e, link)) { \
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if (((t) == 0 || e->type == (t)) && \
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strcasecmp(e->key, (k)) == 0) \
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break; \
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} \
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}
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isc_result_t
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isc_symtab_lookup(isc_symtab_t *symtab, const char *key, unsigned int type,
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isc_symvalue_t *value) {
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unsigned int bucket;
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elt_t *elt;
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REQUIRE(VALID_SYMTAB(symtab));
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REQUIRE(key != NULL);
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FIND(symtab, key, type, bucket, elt);
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if (elt == NULL) {
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return ISC_R_NOTFOUND;
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}
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SET_IF_NOT_NULL(value, elt->value);
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return ISC_R_SUCCESS;
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}
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static void
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grow_table(isc_symtab_t *symtab) {
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eltlist_t *newtable;
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unsigned int i, newsize, newmax;
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REQUIRE(symtab != NULL);
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newsize = symtab->size * 2;
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newmax = newsize * 3 / 4;
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INSIST(newsize > 0U && newmax > 0U);
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newtable = isc_mem_cget(symtab->mctx, newsize, sizeof(eltlist_t));
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for (i = 0; i < newsize; i++) {
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INIT_LIST(newtable[i]);
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}
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for (i = 0; i < symtab->size; i++) {
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elt_t *elt, *nelt;
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for (elt = HEAD(symtab->table[i]); elt != NULL; elt = nelt) {
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unsigned int hv;
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nelt = NEXT(elt, link);
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UNLINK(symtab->table[i], elt, link);
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hv = hash(elt->key, symtab->case_sensitive);
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APPEND(newtable[hv % newsize], elt, link);
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}
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}
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isc_mem_cput(symtab->mctx, symtab->table, symtab->size,
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sizeof(eltlist_t));
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symtab->table = newtable;
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symtab->size = newsize;
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symtab->maxload = newmax;
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}
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isc_result_t
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isc_symtab_define(isc_symtab_t *symtab, const char *key, unsigned int type,
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isc_symvalue_t value, isc_symexists_t exists_policy) {
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unsigned int bucket;
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elt_t *elt;
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REQUIRE(VALID_SYMTAB(symtab));
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REQUIRE(key != NULL);
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REQUIRE(type != 0);
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FIND(symtab, key, type, bucket, elt);
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if (exists_policy != isc_symexists_add && elt != NULL) {
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if (exists_policy == isc_symexists_reject) {
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return ISC_R_EXISTS;
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}
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INSIST(exists_policy == isc_symexists_replace);
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UNLINK(symtab->table[bucket], elt, link);
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if (symtab->undefine_action != NULL) {
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(symtab->undefine_action)(elt->key, elt->type,
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elt->value,
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symtab->undefine_arg);
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}
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} else {
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elt = isc_mem_get(symtab->mctx, sizeof(*elt));
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ISC_LINK_INIT(elt, link);
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symtab->count++;
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}
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/*
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* Though the "key" can be const coming in, it is not stored as const
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* so that the calling program can easily have writable access to
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* it in its undefine_action function. In the event that it *was*
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* truly const coming in and then the caller modified it anyway ...
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* well, don't do that!
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*/
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elt->key = UNCONST(key);
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elt->type = type;
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elt->value = value;
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/*
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* We prepend so that the most recent definition will be found.
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*/
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PREPEND(symtab->table[bucket], elt, link);
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if (symtab->count > symtab->maxload) {
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grow_table(symtab);
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}
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return ISC_R_SUCCESS;
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}
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isc_result_t
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isc_symtab_undefine(isc_symtab_t *symtab, const char *key, unsigned int type) {
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unsigned int bucket;
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elt_t *elt;
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REQUIRE(VALID_SYMTAB(symtab));
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REQUIRE(key != NULL);
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FIND(symtab, key, type, bucket, elt);
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if (elt == NULL) {
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return ISC_R_NOTFOUND;
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}
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if (symtab->undefine_action != NULL) {
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(symtab->undefine_action)(elt->key, elt->type, elt->value,
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symtab->undefine_arg);
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}
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UNLINK(symtab->table[bucket], elt, link);
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isc_mem_put(symtab->mctx, elt, sizeof(*elt));
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symtab->count--;
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return ISC_R_SUCCESS;
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}
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unsigned int
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isc_symtab_count(isc_symtab_t *symtab) {
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REQUIRE(VALID_SYMTAB(symtab));
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return symtab->count;
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}
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